Musk's fortune rose more than $ 6 billion on Friday, according to Bloomberg, after Tesla's stock jumped 10.8% to a record $ 1,544 a share. Its market value was $ 286.5 billion.
Musk owns 20.8% of Tesla's stock, making his stake worth just under $ 60 billion. Musk is also the main shareholder of SpaceX, a private tunnel company.
Buffett's fortune fell this week after donating nearly $ 3 billion in Berkshire Hathaway stock to charity - part of his plan to donate most of his wealth to philanthropic businesses.
Tesla's shares have risen more than 500% in the past 12 months, surpassing the value of almost every company in the S&P 500. The electric car maker is the most valuable car company in the world.
Musk, 49, could possibly become the wealthiest person in the world - a place currently occupied by Amazon CEO Jeff Bezos - based on compensation that Tesla shareholders approved in 2018.
In late May, Tesla today granted Musk stock options worth $ 1.8 billion. Now he's about to start again - for a second time in just over two months.
Musk's compensation plan presents a plan that could potentially give him 20.3 million stock options over the next 10 years.
- Chris Isidore of CNN Business contributed to the reports.
